Celtic have made American goalkeeper Brad Guzan an offer to sign for the club - but manager Gordon Strachan denies it means number one Artur Boruc will be leaving Parkhead.

The Poland international, who is a hero to the Hoops fans, recently extended his contract with the Clydesdale Bank Premier League champions until 2011 but has admitted in the past his ultimate ambition is to play in the Barclays Premier League.

Guzan, 23, arrived in Scotland at the beginning of the week after playing for his country in a 2-0 friendly win over Sweden and the Chivas USA keeper and impressed Strachan.

However, the Hoops boss denied the offer made to him means the sale of Boruc in the near future.

"I hadn't thought about that. I'm thinking about Brad as an investment for the future," he said.

"If you can get someone who could be good value for years to come then you do it."

Strachan also confirmed 22-year-old Japan midfielder Koki Mizuno will arrive in Glasgow soon.

He said: "The arrangements are nearly completed and it looks like he will be here before the window closes.

"I think the future looks very positive."

Strachan, whose side face Falkirk in the SPL tomorrow, has dismissed reports Portsmouth want left-back Lee Naylor, claiming Burnley's failed attempt to land Derek Riordan for £400,000 has been the only firm bid for anyone the club have received.

"The only direct offer was for Derek Riordan. That is not going to happen for that price and it is not going to happen because I trusted him to play in an emergency last week and he did well," added the Celtic boss.

However, Burnley manager Owen Coyle is reluctant to admit defeat just yet.

"We thought it was a fair and realistic offer but it was turned down and you can't argue with that," he told Radio Clyde.

"It was a chance to kick-start his career but it has not materialised. He is a player that I obviously have a high opinion of and I think he would do well for us at Burnley.

"I don't know if I will revisit it, I will have to speak to the powers-that-be in terms of the finance but you never say never in football."